Hydration dependent biomechanical properties of the corneal stroma
Hydration dependent biomechanical properties of the corneal stroma
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DOI：
10.1016/j.exer.2013.07.016
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发表时间：
2013-11-01
影响因子：
3.4
通讯作者：
Etebu, Ebitimi
中科院分区：
文献类型：
--
作者：
Hatami-Marbini, Hamed;Etebu, Ebitimi
角膜负责眼睛约百分之七十的屈光力，并传输百分之九十以上的入射光。角膜的屈光力和透明度在很大程度上取决于其精确曲率和高度规则的微观结构的积极维持。角膜的生物力学特性主要来源于基质层。在过去的几十年中，已经提出了许多计算模型来预测正常和/或患病状态下的角膜行为。这些数值方法的预测很大程度上依赖于对角膜力学特性的准确描述。本研究使用无侧限压缩技术来表征角膜材料参数对由于水合/脱水而导致的厚度变化的依赖性。对猪角膜纽扣进行了一系列无侧限压缩试验，获得了样品的应力松弛响应。使用横向各向同性双相模型来分析每个斜坡和保持步骤的实验测量结果。样品的面内杨氏模量、面外（横向）杨氏模量和渗透系数被确定为平均厚度的函数。由于溶胀（或脱水）而导致的平均厚度变化在 0.69 毫米至 1.27 毫米之间。研究发现，角膜材料参数很大程度上取决于组织厚度（水合作用）。特别是，面内弹性模量随着厚度的减小而增大（p < 0.05），而渗透系数随着厚度的减小而减小（p < 0.05）。此外，据观察，虽然平均厚度在 1.07 mm 和 1.27 mm 之间变化时面外模量几乎恒定，但组织厚度超出该范围时面外模量会增加 (p < 0.05)。这项研究的结果提供了有关角膜基质生物力学特性的重要信息，并且可用于角膜的计算模拟。 (C) 2013 Elsevier Ltd. 保留所有权利。
The cornea is responsible for about seventy percent of refractive power of the eye and transmits more than ninety percent of the incident light. The refractive power and transparency of the cornea are largely contingent upon active maintenance of its precise curvature and highly regular microstructure. The biomechanical properties of the cornea are mainly derived from the stromal layer. Over past decades, many computational models have been proposed to predict the corneal behavior in normal and/or diseased state. The predictions of these numerical methods strongly depend on accurate description of corneal mechanical properties. The present study used unconfined compression technique to characterize the dependence of corneal material parameters on thickness variations due to hydration/dehydration. A series of unconfined compression tests was performed on porcine corneal buttons and stress relaxation response of the samples was obtained. A transversely isotropic biphasic model was used to analyze experimental measurements at each ramp-and-hold step. The in-plane Young's modulus, out-of-plane (transverse) Young's modulus, and permeability coefficient of the samples were determined as a function of average thickness. The average thickness variation due to swelling (or dehydration) was between 0.69 mm and 1.27 mm. It was found that corneal material parameters depend strongly on the tissue thickness (hydration). In particular, the in-plane elastic modulus increased with decreasing the thickness (p < 0.05) and the permeability coefficient decreased with decreasing the thickness (p < 0.05). Furthermore, it was observed that although the out-of-plane modulus was almost constant as the average thickness varied between 1.07 mm and 1.27 mm, it increased with tissue thickness outside this range (p < 0.05). The findings of this study provide important information on biomechanical properties of corneal stroma and are useful in computational simulations of the cornea. (C) 2013 Elsevier Ltd. All rights reserved.